#include <iostream>
#include <cmath>

using namespace std;

void distance(int x1, int y1, int x2, int y2);

int main(void)
{
	int x1, y1, x2, y2;
	cout << "x1 = ";
	cin >> x1;
	cout << "y1 = ";
	cin >> y1;
	cout << "x2 = ";
	cin >> x2;
	cout << "y2 = ";
	cin >> y2;

	distance(x1, y1, x2, y2);

	return 0;
}

void distance(int x1, int y1, int x2, int y2)
{
	double distance;
	distance = sqrt(pow(x1 - x2, 2) + pow(y1 - y2, 2));
	cout << "distance = " << distance << endl;
}
